Endless driven sprocket chains are commonly used in many different types of machinery. Such chains form an endless loop using a multiplicity of interleaved inner and outer chain links. Inner chain links couple to outer chain links using a pivot pin or the equivalent to allow individual inner links to rotate relative to outer links about pivot points. Driving sprockets and the like engage the chains, typically at their inner links, to impart motion to the chains. Driven sprockets, idler gears, and the like may receive rotational motion as the chains move. As the chains' movement causes the chains to curve around sprockets, inner and/or outer chain links pivot around the pivot pins so that the chains' shape conforms to the shape of the sprockets. Examples of such chains include bicycle chains, motorcycle chains, chain saw blades, and trench digger blades.
Conventional endless driven sprocket chains allow inner links to freely pivot about the pivot pins, at least for the range of motion experienced by the chains in normal operation. This unrestrained pivoting leads to several undesirable consequences. For example, chain tensioning mechanisms are often needed to maintain a proper amount of chain tension. Such chain tensioning mechanisms are usually considered to be relatively expensive, unreliable, and complex. If chain tension mechanisms are omitted, then chains often operate in either a too loose or too tight condition, and both conditions lead to excessive wear and tear.
In addition, an excessive amount of driving force is expended in causing a conventional chain to rotate around sprockets, and this limits chain speed and overall efficiency. This factor is particularly troublesome when the chain tends to experience a load or impacts at the point where the chain changes directions, such as occurs with trench digging chains. In such conditions, conventional chains typically operate in a highly tightened state, which leads to driving inefficiencies.